Simulation is one of the most powerful tools available in medical education. We have numerous studies showing the benefit and efficacy of simulation as a way to improve learning, procedural skill, and patient safety. Even with all of the potential benefits of simulation, the hardest lesson in simulation is learning when not to use it, or identifying how to change your approach to improve learning and the take home message. Standards have been written and publications look better with positive results, but not all educational approaches in simulation have been successful. This talk outlines best-practices for simulation and discusses when you might encounter problems in the implementation or takeaway from simulation and how to address these potential problems.